iommu: Add helpers to set/get default domain type

Add a couple of functions to allow changing the default
domain type from architecture code and a function for iommu
drivers to request whether the default domain is
passthrough.
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -2213,6 +2213,28 @@ int iommu_request_dma_domain_for_dev(struct device *dev)
 	return request_default_domain_for_dev(dev, IOMMU_DOMAIN_DMA);
 }
 
+void iommu_set_default_passthrough(bool cmd_line)
+{
+	if (cmd_line)
+		iommu_set_cmd_line_dma_api();
+
+	iommu_def_domain_type = IOMMU_DOMAIN_IDENTITY;
+}
+
+void iommu_set_default_translated(bool cmd_line)
+{
+	if (cmd_line)
+		iommu_set_cmd_line_dma_api();
+
+	iommu_def_domain_type = IOMMU_DOMAIN_DMA;
+}
+
+bool iommu_default_passthrough(void)
+{
+	return iommu_def_domain_type == IOMMU_DOMAIN_IDENTITY;
+}
+EXPORT_SYMBOL_GPL(iommu_default_passthrough);
+
 const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
 {
 	const struct iommu_ops *ops = NULL;

include/linux/iommu.h

@@ -436,6 +436,9 @@ extern void iommu_get_resv_regions(struct device *dev, struct list_head *list);
 extern void iommu_put_resv_regions(struct device *dev, struct list_head *list);
 extern int iommu_request_dm_for_dev(struct device *dev);
 extern int iommu_request_dma_domain_for_dev(struct device *dev);
+extern void iommu_set_default_passthrough(bool cmd_line);
+extern void iommu_set_default_translated(bool cmd_line);
+extern bool iommu_default_passthrough(void);
 extern struct iommu_resv_region *
 iommu_alloc_resv_region(phys_addr_t start, size_t length, int prot,
 			enum iommu_resv_type type);
@@ -736,6 +739,19 @@ static inline int iommu_request_dma_domain_for_dev(struct device *dev)
 	return -ENODEV;
 }
 
+static inline void iommu_set_default_passthrough(bool cmd_line)
+{
+}
+
+static inline void iommu_set_default_translated(bool cmd_line)
+{
+}
+
+static inline bool iommu_default_passthrough(void)
+{
+	return true;
+}
+
 static inline int iommu_attach_group(struct iommu_domain *domain,
 				     struct iommu_group *group)
 {